Deployment options
At Activision Publishing, one of Fenady's initial concerns turned out to be a non-issue. "The Riverbed [Steelhead appliances] moved everything onto proprietary ports," says Fenady, while other products "kept everything on native ports." With a Steelhead appliance at both ends of the WAN (he started with one at the California headquarters and another in Dublin, Ireland), Fenady discovered that his traffic was now moved to a single, proprietary port. "So then you need NetFlow [the proprietary network protocol developed by Cisco Systems Inc. for collecting traffic information]," he says. By enabling NetFlow on the Riverbed appliance, Fenady sees what he needs to. Primarily, Fenady wants up-to-date numbers related to bandwidth utilization; for troubleshooting, he likes to dig deeper into traceroutes, retransmits and cyclic redundancy checks.

Getting the most out of a WAN optimization product, says Fenady, comes down to deciding how to deploy it. The leading WAN optimization vendors support two classes of deployment: in-path and out-of-path (see "In-path vs. Out-of-path WAN optimization," below).


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In-path vs. Out-of-path WAN optimization
WAN optimization customers typically have two choices for deployment: in-path or out-of path. Out-of-path deployments are more technically challenging, and while there are no pre-set conditions for determining which deployment method is better for a single IT shop, out-of-path deployments are sometimes the first choice of companies that choose to accelerate particular subsets of their traffic--applications or routes they know are tying up bandwidth.

An out-of-path deployment is also a likely choice for data centers where there's no obvious single point at which in-path appliances should be deployed. When deploying out-of-path, users decide on protocols: Policy-based routing (PBR) or the more common Web Cache Communications Protocol (WCCP). WCCP does consume some memory and CPU cycles on the router or switch. For some, that's a non-issue. With older-series routers, that might be a problem.

With in-path deployments, things are simpler. There are no routers to configure, and no memory to add. In a single-path deployment, the NICs are "fail-to-wire," explains John Martin, VP of product management at Riverbed Technology Inc. "In other words, if there's a software or hardware failure, the NICs become a wire and the traffic passes straight through as if the device wasn't there," he says. Approximately 70% of Riverbed customers deploy their appliances in-path, he adds. Examples of an in-path deployment and out-of-path deployment are shown here.

In an in-path deployment, an appliance is inserted between the WAN router and the Ethernet switch on the LAN side of the network.


Out-of-path deployment of a WAN optimization appliance with the Web Cache Communications Protocol (WCCP).

Diagram source: Silver Peak

This was first published in September 2008

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